Rheostat.



W. G. ABBOTT, JR.

RHEOSTAT.

APPLICATION FILED JULY s, 1907.

Patented June 22, 1909.

UM/7 y Nnnms PETERS. INC.. LlTHo.. WASHINGTQN. D. C

UNITED sTATEs PATENT oEEicE.

WILLIAM G. A DOTT, JR., OF SGHENEOTADY, NEW YORK, ASSIGNOR IOGENERAL i'zlLlCTRIC COMPANY, A CORPORATION OF NEW YORK.

RHEOSTAT.

Specification of Letters Patent.

latented June 22, 1909.

Application med .my a, 11907. sei-iai No, 381,996.

To all whom it inay'concern:

Be it known that I, WILLIAM G. ABBOTT, Jr., a citizen ofthe United States, residing at Schenectady, county of. Schenectady, State 'of Xew York, have invented certain new and useful Improvements in Rheostats, of which the following is a specilication.

`the form of a resistance stick is employed in combination with a sliding controlling inem@ ber. y V

In carrying out my invention, I provide in connection with the resistance stick and sliding contact, means for keeping the stick cool. I accomplish this result by arranging a passage for cooling fluid through the rod. The rod is made of high resistance material, preferably molded, and is hollow, the connections being made so that the water is caused to How through the' rod. The controlling member is made in the form of a ring having radial brushes so it is movable both longitudinally and circumterentially, and a pivoted handle'makes it conveniently operative from various positions.

l In the accompanyingdrawing in which I have shown my invention embodied in a specilic structure, Figure 1 is a plan viewvot' .my device; Fig. 2 is a side elevation of the same and Fig. 3 is section showing the controlling member and pivoted operating handle.

' Referringto the drawing, 10 is a base, preferablyot insulating material, upon which are mounted. two supports 1l. and l for supporting the resistance rod 13. rl`his rod is preterably made ot' high resistance refractory material. rl`-he particular compo-.ahlen of this resista-nce stick forms no part ot my invention. I have l'ound, however, that carborundum clay made into thc desired pe serves very well my purpose. I have l'ornied a compound very desirable iorthis purpose by mixing about 75% blue clay, '15076 spar, 8%

llint and 2% cryolite into a base and nnxing omitted.

' simple rheostat capable of giving a high resist-v ab'out the following proportions: base 41%, carborundum 41% and graphite '18%. In cases where it is desired that avery high resistance be obtained, the graphite may be These materials are molded into the desired form and baked ata high temperature. This rod is prefer` .,iy made holow as shown and is mounted in supports by means of clips 1a and 15. One of these clips l-'is yielding so as to permit or an easy removal of the rod as well as to allow for expansion and contraction. .si clamp 16 surrounding the clip holds the rod securely in place.. The clips pass through the supports 11 and 12 and at their outer-extremities are provided with means for attaching a pipe or hose, being in this case merely nipples 17 and 18 for attaching a flexible hose.

The controlling member comprises a ring support 19, preferably ot metal, in the interior of which are supported a'plurality of contacts .or brushes 2O adapted to bear upon the rod and arranged substantially radial thereto. I have shown a' large number ot' these brushes so that they torni practically a continuous ring upon the rod. This gives, a very elicient contactbut a smaller number of brushes may be used it desired. An operating handle 21 is pivoted on opposite sides of the ring on bearing screws 22so that the brushes may be moved bot-h longitudinally and circumterentially of the rod. This construction facilitates operation from various l Apositions "ithout placing undue strain upon the resistance rod and at the same time Agives uniform cont act as well as uniform wear uponv the rod. The circuit connections are made at 23 and 24 on the supporting base and the controlling member respectively.

It will be seen that I have provided a very ance without excessive heat andthe lluid in passing through the rod keeps it cool. 4It' water is used there is a certain amount of leakage through the water, but this will be ollsctf'by the high current density at which thc resistance may be'run because ot' the cooling arrangement. y

The4 resistance rods may, of course, be molded so as to have dill'erent speci'lic resistances and made of various sizes and forms as desired.

It will be understood, ot' course, that I do not limit my invention to the specific construction herein shown eX'cept in so far' as it' is limited by the sco/pe of the claims annexed hereto.

What I claim as n eW and desire to secure by Letters Patentof the United States, is,-

1'. In a rlieostat the combination with a `hollow resistance rod7 of controlling means 'therefor comprising 'a revoluble ring surrounding the rod, and aplurality of vlaminated brushes mounted thereinand vextend- 'ing radially into engagement with therod.

2. A rheostat comprising a resistan'clel rod,

arevoluble supporting ring surrounding the same, a plurality of contact brushes mounted m said ring and .arraneed to. engagef'the1rod, and an operating handle pivoted'to said ring.

3. A'rheostat comprising a highresistance l rod, and a controlling member in slidingenthereof.

5. A rheostat comprising a high resistance I rod, a support surrounding the same having `a plurality of brushes mounted therein subi: through to .cool the saine,

ranged' substantially radi .stantially radial to said rod-[and means for moving said brushes longitudinally and circumferentially f said rod.

6. A rheostatcomprising rod; means forpassing rod to cool the same, and a controlling meme av high resistance 'a iiuid through the bel' having 'a pluralityof ilexible contacts ar-2' v 'ranged substantially .radial to said rod and mounted for longitudinal and circuinterend A tial movement. thereof,

' 7 A rheostat com rising a hollow highsistancerod, means' or passin an a controlling member having `a plurahly mounted for vlongitudinal and circumferential moveinentthereof.-- f 8.5111 a rheostat, the combination with -a hollow resistance rod comprising a compound 'of conducting and'non-icond'ucting material,- vof"acontrolling member in sliding engagement with said rod and mounted for longitudinal and circumferential movement.

Inwitness Whereofyl have hereunto set myfv hand this 28th da'yof June, 1907. i WILLIAM ABBOTT, JR.

Vlitnesses:4

BENJAMIN B. HULL, HELEN Onronn.

a fluid there- 

